Coronary stent thrombosis: beware of an allergic reaction and of Kounis syndrome

Potential Effects of Bisphenol A on the Heart and Coronary Artery of Adult Male Rats and the Possible Role of L-Carnitine

Bisphenol A (BPA) is an environmental toxin utilized for the production of polycarbonate plastics and epoxy resins. Due to BPA's extensive production and environmental contamination, human exposure is unavoidable. The effects of low-dose of BPA on various body tissues and organs remain controversial. Our study investigated the potential of BPA to induce biochemical, histopathological, and immunohistochemical changes in the coronary artery and myocardium and the potential protective role of L-carnitine (LC). 24 adult Wistar albino male rats were divided equally into a control group, a BPA-treated group (40 mg/kg/d, by gavage for 4 weeks), and a BPA plus LC-treated group (received 40 mg/kg/d of BPA and 300 mg/kg/d of LC, by gavage for 4 weeks). BPA-exposed rats demonstrated structural anomalies in the coronary artery tissue including vacuolation of cells in the media and detachment of the endothelium of the intima. Congestion of blood vessels and infiltration by polynuclear cells were observed in the myocardium. There was an enhanced collagen deposition in both tissues indicating fibrosis. Immunohistochemical changes included enhanced eNOS and caspase-3 expression in the coronary artery and myocardium indicating vascular disease and apoptosis, respectively. Oxidative damage was evident in the coronary artery and the myocardium of BPA-treated rats, which was indicated by the reduced level of glutathione (GSH) and elevated malondydehyde (MDA) levels. The coadministration of LC significantly improved BPA-induced structural alterations and oxidative stress. In conclusion, BPA could potentially cause pathologic changes and oxidative damage in the coronary artery and myocardium, which could be improved by LC coadministration.

Cardiogenic Shock due to Kounis Syndrome following Cobra Bite

Kounis syndrome is associated with mast cell activation resulting in acute coronary syndrome secondary to an allergic insult. Various drugs such as antibiotics, analgesics, and environmental exposures such as bee, wasp sting, and poison ivy are known to induce Kounis syndrome. A 68-year-old man admitted with a cobra bite on both hands to emergency care unit and sustained cardiorespiratory arrest. Electrocardiogram, taken 6 hours after the cardiac arrest, showed ST elevations in leads V₂ to V₅ suggestive of anterior ST elevation myocardial Infarction (STEMI). Serum Troponin was 10 ng/ml (control= <0.5). Serum IgE levels were significantly high (19155IU/ml, baseline 100). 2-Dimensional echocardiogram showed anterior and apical-septal hypokinesia with left ventricular ejection fraction of 30-35%. Coronary angiogram was normal. He remained hypotensive requiring inotropic and vasopressor support during ICU stay. This was a case of Kounis syndrome leading to cardiogenic shock secondary to Cobra (naja naja) bite. This is the only reported case of cobra bite causing Kounis syndrome and cardiogenic shock. Identification of the cause of myocardial infarction in snake envenomation is useful in the management as some of the drugs like adrenaline, morphine, and beta blockers may worsen the clinical syndrome if it is due to Kounis syndrome.

Nanoglass-based balloon expandable stents

Here, a prototypical metallic nanoglass is proposed as a new alloy for balloon expandable stents. Traditionally, the stainless steel SS 316L alloy has been used as a preferred material for this application due to its proper combination of mechanical properties, corrosion resistance, and biocompatibility. Recently, metallic glasses (MGs) have been considered as promising materials for biodevice applications. MGs often display outstanding mechanical properties superior to those of conventional metallic alloys and overcome some of the weaknesses of SS 316L, such as radiopacity, stainless steel allergy, and thrombosis-induced restenosis. However, commonly used monolithic MGs, which have an amorphous homogeneous microstructure, suffer from lack of ductility that is necessary for deployment of balloon expandable stents. In contrast, nanoglasses, that is, amorphous alloys with heterogeneous microstructure, exhibit enhanced ductility which makes them promising materials for balloon expandable stents. We evaluate the feasibility of a prototypical Zr₆₄ Cu₃₆ nanoglass with a grain size of 5 nm for balloon expandable stents by performing finite element method modeling of the stent deployment process in a coronary artery. We consider the BX-Velocity stent design and the nanoglass mechanical properties calculated from atomistic simulations. The results suggest that nanoglasses are suitable materials for balloon expandable stent applications. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:73-79, 2020.

Potential Toxic Effect of Bisphenol A on the Cardiac Muscle of Adult Rat and the Possible Protective Effect of Omega-3: A Histological and Immunohistochemical Study

Bisphenol A (BPA) is intensely used in the production of polycarbonate plastics and epoxy resins. Recently, BPA has been receiving increased attention due to its link to various health problems that develop after direct or indirect human exposure. Previous studies have shown the harmful effect of high doses of BPA; however, the effect of small doses of BPA on disease development is controversial. The aim of this study was to investigate the effect of a low dose of BPA on the rat myocardium and to explore the outcome of coadministration of Omega-3 fatty acid (FA). Thirty adult male rats were divided equally into control group, BPA-treated group (1.2 mg/kg/day, intraperitoneally for 3 weeks), and BPA and Omega-3-treated group (received BPA as before plus Omega-3 at a daily dose of 300 mg/kg/day orally) for 3 weeks. Exposure to BPA resulted in structural anomalies in the rat myocardium in the form of disarrangement of myofibers, hypertrophy of myocytes, myocardial fibrosis, and dilatation of intramyocardial arterioles. On the other hand, mast cell density and media-to-lumen area ratio were not significantly altered. Interestingly, concomitant administration of Omega-3 FAs with BPA significantly reduced BPA-induced changes and provided a protective effect to the myocardium. In conclusion, exposure to a low dose of BPA could potentially lead to pathological alterations in the myocardium, which could be prevented by administration of Omega-3 FA.

Allergic recurrent coronary stent thrombosis: A mini-review of Kounis syndrome

Kounis syndrome (KS) consists of an association between hypersensitivity reactions triggered by various environmental and pharmacological factors and acute coronary syndromes. Blood supply may be compromised by either vasospasm (type I), native plaque destabilization (type II) or stent thrombosis (type III). Although the prognosis is generally favorable, treatment should include aggressive anti-thrombotic and anti-allergic therapies. A case compatible with type III KS, manifested as a macular rash followed by two episodes of stent thrombosis after primary angioplasty (PCI) of the right coronary artery is presented, and complemented by a review on the topic.

A Critical Review on Metallic Glasses as Structural Materials for Cardiovascular Stent Applications

Functional and mechanical properties of novel biomaterials must be carefully evaluated to guarantee long-term biocompatibility and structural integrity of implantable medical devices. Owing to the combination of metallic bonding and amorphous structure, metallic glasses (MGs) exhibit extraordinary properties superior to conventional crystalline metallic alloys, placing them at the frontier of biomaterials research. MGs have potential to improve corrosion resistance, biocompatibility, strength, and longevity of biomedical implants, and hence are promising materials for cardiovascular stent applications. Nevertheless, while functional properties and biocompatibility of MGs have been widely investigated and validated, a solid understanding of their mechanical performance during different stages in stent applications is still scarce. In this review, we provide a brief, yet comprehensive account on the general aspects of MGs regarding their formation, processing, structure, mechanical, and chemical properties. More specifically, we focus on the additive manufacturing (AM) of MGs, their outstanding high strength and resilience, and their fatigue properties. The interconnection between processing, structure and mechanical behaviour of MGs is highlighted. We further review the main categories of cardiovascular stents, the required mechanical properties of each category, and the conventional materials have been using to address these requirements. Then, we bridge between the mechanical requirements of stents, structural properties of MGs, and the corresponding stent design caveats. In particular, we discuss our recent findings on the feasibility of using MGs in self-expandable stents where our results show that a metallic glass based aortic stent can be crimped without mechanical failure. We further justify the safe deployment of this stent in human descending aorta. It is our intent with this review to inspire biodevice developers toward the realization of MG-based stents.

Thrombotic responses to coronary stents, bioresorbable scaffolds and the Kounis hypersensitivity-associated acute thrombotic syndrome

Percutaneous transluminal coronary angioplasty with coronary stent implantation is a life-saving medical procedure that has become, nowadays, the most frequent performed therapeutic procedure in medicine. Plain balloon angioplasty, bare metal stents, first and second generation drug-eluting stents, bioresorbable and bioabsorbable scaffolds have offered diachronically a great advance against coronary artery disease and have enriched our medical armamentarium. Stented areas constitute vulnerable sites for endothelial damage, endothelial dysfunction, flow turbulence, hemorheologic changes, platelet dysfunction, coagulation changes and fibrinolytic disturbances. Implant surface attracts several proteins such as albumin, fibronectin, fibrinogen, and complement that lead to complement system activation. Macrophages recognize the implant as foreign substance due to protein adsorption and its continuous presence results in macrophage differentiation and fusion into foreign body giant cells. Polymer coating, stent metallic platforms and the released drugs can act as strong antigenic complex that apply continuous, repetitive, persistent and chronic hypersensitivity irritation to the coronary intima. The concomitant administration of oral antiplatelet drugs and environmental exposures can induce hypersensitivity inflammation. A class of platelets, activated via high-affinity and low-affinity IgE hypersensitivity receptors FCγRI, FCγRII, FCεRI and FCεRII, can induce Kounis hypersensitivity-associated thrombotic syndrome inside the stented coronaries. Type III variant of this syndrome is diagnosed when coronary artery stent thrombosis is associated with thrombus infiltrated by eosinophils or mast cells and/or when coronary intima, media and adventitia adjacent to stent, is infiltrated by eosinophils or mast cells. Careful history of hypersensitivity reactions to all implanted materials and concomitant drugs with monitoring of inflammatory mediators as well as lymphocyte transformation studies to detect hypersensitivity must be undertaken in order to avoid disastrous consequences. Food and Drug Administration recommendations for coronary stent implantation should be applied also to bioresorbable scaffolds. Further studies with inert and non-allergenic implants are necessary.

Early stent thrombosis secondary to food allergic reaction: Kounis syndrome following rice pudding ingestion

Kounis syndrome is the concurrence of coronary spasm, acute myocardial infarction or stent thrombosis, with allergic reactions in the setting of mast-cell and platelet activation. In this report Kounis syndrome manifesting as stent thrombosis with left ventricular thrombus formation was triggered by a food-induced allergic reaction. The allergic reaction to food was confirmed by oral rice pudding ingredients challenge test while skin tests were inconclusive. To our knowledge, this is first report of early stent thrombosis secondary to food allergic reaction in a 70-year-old man patient who was found to have left ventricular thrombus and undiagnosed hypertrophic cardiomyopathy.

Pharmacokinetic drug interactions with clopidogrel: updated review and risk management in combination therapy

Background

Coprescribing of clopidogrel and other drugs is common. Available reviews have addressed the drug–drug interactions (DDIs) when clopidogrel is as an object drug, or focused on combination use of clopidogrel and a special class of drugs. Clinicians may still be ignorant of those DDIs when clopidogrel is a precipitant drug, the factors determining the degree of DDIs, and corresponding risk management.

Methods

A literature search was performed using PubMed, MEDLINE, Web of Science, and the Cochrane Library to analyze the pharmacokinetic DDIs of clopidogrel and new P2Y₁₂ receptor inhibitors.

Results

Clopidogrel affects the pharmacokinetics of cerivastatin, repaglinide, ferulic acid, sibutramine, efavirenz, and omeprazole. Low efficacy of clopidogrel is anticipated in the presence of omeprazole, esomeprazole, morphine, grapefruit juice, scutellarin, fluoxetine, azole antifungals, calcium channel blockers, sulfonylureas, and ritonavir. Augmented antiplatelet effects are anticipated when clopidogrel is coprescribed with aspirin, curcumin, cyclosporin, St John’s wort, rifampicin, and angiotensin-converting enzyme inhibitors. The factors determining the degree of DDIs with clopidogrel include genetic status (eg, cytochrome P540 [CYP]2B6*6, CYP2C19 polymorphism, CYP3A5*3, CYP3A4*1G, and CYP1A2-163C.A), species differences, and dose strength. The DDI risk does not exhibit a class effect, eg, the effects of clopidogrel on cerivastatin versus other statins, the effects of proton pump inhibitors on clopidogrel (omeprazole, esomeprazole versus pantoprazole, rabeprazole), the effects of rifampicin on clopidogrel versus ticagrelor and prasugrel, and the effects of calcium channel blockers on clopidogrel (amlodipine versus P-glycoprotein-inhibiting calcium channel blockers). The mechanism of the DDIs with clopidogrel involves modulating CYP enzymes (eg, CYP2B6, CYP2C8, CYP2C19, and CYP3A4), paraoxonase-1, hepatic carboxylesterase 1, P-glycoprotein, and organic anion transporter family member 1B1.

Conclusion

Effective and safe clopidogrel combination therapy can be achieved by increasing the awareness of potential changes in efficacy and toxicity, rationally selecting alternatives, tailoring drug therapy based on genotype, checking the appropriateness of physician orders, and performing therapeutic monitoring.